Device for controlling an electric load, and a control device

ABSTRACT

A device for controlling at least one electrical load and a control device therefor. The electrical load includes a first load connection and a second load connection. The first load connection is able to be connected to an operating-voltage potential via a first controlled switch, and the second load connection is able to be connected to a reference voltage potential via a second controlled switch.

FIELD OF THE INVENTION

The present invention relates to a device for controlling at least oneelectrical load and to a control device therefor.

BACKGROUND INFORMATION

Relays in motor vehicles may be controlled by just a single controldevice. It is the terminals of a coil of the electromagnetic actuatorthat are controlled.

SUMMARY OF THE INVENTION

With the exemplary device according to the present invention forcontrolling at least one electrical load and the control deviceaccording to the present invention, exactly only one load terminal isable to be controlled by a controlled switch and may be connected, viathe controlled switch, to precisely one potential, in particular anoperating-voltage potential or a reference voltage potential. In thisway, two controlled switches are required to operate the electrical loadin order to connect one of the two load terminals to theoperating-voltage potential and the other of the two load terminals tothe reference voltage potential, thereby allowing a current flow in theload. If one of the two controlled switches is faulty to the extent thatit is always conducting, the electromagnetic actuator may be controlledvia the other controlled switch. In this way, the switching function ofthe electromagnetic actuator may be ensured in a more optimal and morereliable manner. Moreover, using two controlled switches allows a moredifferentiated control of the load, for example as a function of aplurality of conditions.

A detection circuit, which detects the potential at this load terminal,is connected to at least one of the two load terminals. In this way, theswitching state of the controlled switch triggering the other loadterminal may be ascertained at this load terminal.

An operating mode is provided in which a signaling of one of the twocontrolled switches takes place to the load terminal of the othercontrolled switch in the form of at least one switching state, via theload, and a detection of the voltage resulting therefrom by thedetection circuit at the load terminal of the other controlled switch.The functionality of the load may be increased in this manner so that itnot only leads to the initiation of a load state of the electrical load,but also allows a communication between the control devices controllingthe load terminals. Thus, separate connecting lines between the controldevices for establishing a communication connection may be dispensedwith.

A high-ohmic resistor may be connected in parallel to one of the twoswitches, thereby connecting the load terminals to a defined potential.

This may also be achieved, at least intermittently, in that a high-ohmicresistor may be connected in parallel to one of the two controlledswitches, for example by an associated additional controlled switch, orby switching a switch into a high-ohmic but still conducting state.

In an actuator-operating mode of the device, at least one of thehigh-ohmic resistors is connected in parallel to one of the switchescontrolling the load, so that the switching state of the othercontrolled switch controlling the load is detectable at the loadterminal assigned to this load. Due to the at least one resistorconnected in parallel, a defined potential at the load terminals andthus a reliable detection of the load state may be obtained.

By ascertaining the switching state of the one controlled switch, at thecontrol device of the other controlled switch, it may be detectedwhether a current flow in the load may be effected by the othercontrolled switch and thus, if the load is designed as a coil of anelectromagnetic actuator, a responding electromagnetic actuator. Theother controlled switch may then be triggered as a function of thisinformation. In this way, a differentiated and intelligent control ofthe load is able to be realized in a simple manner.

In a communication operating mode of the device, a communication betweenthe two load terminals takes place via the load, by energizing orde-energizing the particular high-ohmic resistor at the one loadterminal and detecting the voltage resulting therefrom at the respectiveother load terminal. In this way, the communication may be realized viathe load, independent of the controlled switches controlling the loadand thus independent of an activation of an electromagnetic actuator, ifthe load is embodied as coil of such an actuator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first exemplary embodiment of a device according to thepresent invention for triggering an electromagnetic actuator.

FIG. 2 shows a second exemplary embodiment of a device according to thepresent invention for triggering an electromagnetic actuator.

FIG. 3 shows a third exemplary embodiment of a device according to thepresent invention for triggering an electromagnetic actuator.

FIG. 4 shows a fourth exemplary embodiment of a device according to thepresent invention for triggering two electromagnetic actuators.

DETAILED DESCRIPTION

In FIG. 1, the device 1 denotes a device for triggering anelectromagnetic actuator 5, which in this exemplary embodiment isarranged as a relay by way of example, and of which only a coil 20 isshown as an example of an electrical load. A voltage source 95, forinstance a battery of a motor vehicle, lies between a reference-voltagepotential 40, referred to as ground in the following, and an operatingelectric potential 35. Voltage source 95 is provided as voltage supplyfor a first control device 60 and a second control device 65. Coil 20includes a first coil connection 10 and a second coil connection 15.First coil connection 10 is connected to a first connecting contact 75of first control device 60, first connecting contact 75 constituting thesingle connecting contact of a first control terminal 70 of firstcontrol device 60 for the triggering of relay 5. Second coil connection15 is connected to a second connecting contact 76 of second controldevice 65, second connecting contact 76 forming the single connectingcontact of a second control terminal 71 of second control device 65 forthe triggering of relay 5.

On one side, first connecting contact 75 is connected to a firstdetection circuit 45 of first control device 60. On the other side,first connecting contact 75 may be connected to operating-voltagepotential 35 via a first controlled switch 25 of first control device60. Second connecting contact 76 is connected to a second detectioncircuit 46 of second control device 65 on one side, and secondconnecting contact 76 is able to be connected to ground via a secondcontrolled switch 30 of second control device 65 on the other side.Furthermore, first control device 60 includes a first control 100 towhich first detection circuit 45 is connected and which triggers firstcontrolled switch 25.

Second control device 65 includes a second control 105 to which seconddetection circuit 46 is connected and which triggers second controlledswitch 30. According to FIG. 1, both controlled switches 25, 30 areembodied as field-effect transistors by way of example. However, one ofthe two controlled switches 25, 30 or both controlled switches 25, 30may also have any other design known to one skilled in the art, and beembodied as bipolar transistors, for example.

In an actuator-operating mode or a relay-operating mode, the twocontrolled switches 25, 30 are used to trigger coil 20 of relay 5. Assoon as both controlled switches 25, 30 are closed, i.e., are broughtinto the conductive state, a current begins to flow through coil 20 ofrelay 5, and relay 5 is switched. As soon as one of the two controlledswitches 25, 30 is opened, i.e., brought into the disabled state, thecurrent flow through coil 20 of relay 5 is interrupted and relay 5 isswitched back.

In this way, the switching of relay 5 may be tied to two conditions.When these are satisfied, first control 100 brings first control 100into the conductive state and second control 105 brings secondcontrolled switch 30 into the conductive state as well. If only one ofthe two conditions is not satisfied, one of the two controlled switches25, 30 is triggered such that it blocks, so that relay 5 is unable to beswitched and is present in the switched-back state. If a load isswitched into a load-current circuit by the switching of relay 5, thismay be made dependent on the simultaneous satisfaction of the twoconditions.

Furthermore, a safety function may be realized by the use of the twocontrolled switches 25, 30. If one of the two controlled switches 25, 30is defective in that it continuously remains in a conductive stateregardless of its triggering, relay 5 may then be switched and switchedback solely by the other, non-defective controlled switch.

If there is a change in the switching state of first controlled switch25, a change in the potential at second connecting contact 76 willoccur, which is detected by second detection circuit 46. Seconddetection circuit 46 is thus able to detect a change in the switchingstate of first controlled switch 25. For example, if first controlledswitch 25 and second controlled switch 30 are initially open and firstcontrolled switch 25 is then closed, the potential at second connectingcontact 76 is adjusted from an initially undefined value toapproximately operating-voltage potential 35. If the initially undefinedpotential is not equal to operating-voltage potential 35, a potentialchange to approximately operating-voltage potential 35 takes place atsecond connecting contact 76 when first controlled switch 25 is closed,which is detected by second detection circuit 46. Second detectioncircuit 46 thus detects a change in the switching state of firstcontrolled switch 25.

If, conversely, given the same original position, i.e., an open firstcontrolled switch 25 and open second controlled switch 30, secondcontrolled switch 30 is closed, the potential at first connectingcontact 75 changes from an undefined potential to approximately ground40, provided the undefined potential was not equal to ground 40. In thisway, this potential change and a switching procedure of secondcontrolled switch 30 are able to be detected in first detection circuit45.

The described detection of switching procedures of first controlledswitch 25 and second controlled switch 30 may also be utilized for acommunication between both control devices 60, 65. This communicationmay occur independently of an activation of relay 5 if it is ensuredthat at least one of the two controlled switches 25, 30 is open at alltimes for the duration of the communication. For instance, by switchingor modifying the switching state of first controlled switch 25, firstcontrol device 60 is able to generate a binary signal, which may bedetected by second detection circuit 46 in second control device 65 viadetection of the individual switching state at second connecting contact76. While first control device 60 in this way transmits a signal tosecond control device 65 via coil 20, second controlled switch 30 isopen. The switching states of first controlled switch 25 are implementedat second connecting contact 76 in the manner described in that thepotential or the voltage level resulting from the individual switchingstate of first controlled switch 25 is detected at second connectingcontact 76.

Conversely, second control device 65 may transmit signals to firstcontrol device 60 via coil 20 in a corresponding manner in that theswitching state of second controlled switch 30 is modified to generate abinary signal, and in that the voltage level or voltage potentialsresulting therefrom are ascertained and evaluated at first connectingcontact 75 by first detection circuit 45. This takes place when firstcontrolled switch 25 is open. In this manner, a bi-directionalcommunication may be established between first control device 60 andsecond control device 65. However, only one of the two control device60, 65 is able to transmit at any one time, whereas the other of the twocontrol devices 60, 65 may only receive during that time. The binarityof the individual transmitted signal results from the defined potentialduring closing of the controlled switch of the transmitting controldevice and, on the other hand, from an undefined potential, whichdiffers from this defined potential, during opening of the controlledswitch of the transmitting control device. The undefined potential,which is different from the defined potential, is viewed like a singlevalue, even if different, undefined potentials may occur during openingof the controlled switch of the transmitting control device.

FIG. 2 shows a second exemplary embodiment of the device according tothe present invention for triggering the relay. Identical referencesigns denote elements that are identical to those in FIG. 1. In contrastto FIG. 1, first detection circuit 45 is integrated in first control 100and second detection circuit 46 is integrated in second control 105.Another difference is that a first high-ohmic resistor 50 is nowconnected in parallel to the breaker gap of first controlled switch 25and a second high-ohmic resistor 55 is connected in parallel to thebreaker gap of second controlled switch 30. The high-ohmic resistance offirst resistor 50 and second resistor 55 are to be selected such thatessentially no current flows through coil 20 when first controlledswitch 25 is open and when second controlled switch 30 is open, and thusno activation of relay 5 takes place.

Using first resistor 50 and second resistor 55 results in the advantagethat a defined potential at first connecting contact 75 and at secondconnecting contact 76, respectively, may at all times be detected byfirst detection circuit 45 and second detection circuit 46 even in thosecases where both controlled switches 25, 30 are open. When bothresistors 50, 55 have approximately the same resistance value, forexample, the potential at first connecting contact 75 and at secondconnecting contact 76 amounts to approximately half of operating-voltagepotential 35 when both controlled switches 25, 30 are open. If firstcontrolled switch 25 is open and second controlled switch 30 closed, apotential corresponding approximately to ground 40 results at firstconnecting contact 75 and at second connecting contact 76. If secondcontrolled switch 30 is open and first controlled switch 25 closed, apotential that corresponds approximately to operating-voltage potential35 comes about at first connecting contact 75 and at second connectingcontact 76.

The functioning method of the exemplary embodiment according to FIG. 2is thus identical to the functioning method of the exemplary embodimentaccording to FIG. 1, with the difference that, in the event that bothcontrolled switches 25, 30 are open, a defined potential at firstconnecting contact 75 and at second connecting contact 76 is ascertainedby first detection circuit 45 and by second detection 46 in the secondexemplary embodiment according to FIG. 2, so that there is no longer anyundefined potential. Given an appropriate selection of the two resistors50, 55, this potential also differs considerably from operating-voltagepotential 35 and ground 40.

A prerequisite is that one of the two resistors 50, 55 is notsubstantially higher than the other one of the two resistors 50, 55.Otherwise this potential is either considerably closer to mass 40 thanto operating-voltage potential 35 or considerably closer tooperating-voltage potential 35 than to mass 40, which may easily beinferred from the voltage divider principle.

Setting a defined potential at first connecting contact 75 and at secondconnecting contact 76 while first controlled switch 25 is open and whilesecond controlled switch 30 is open may be done if only one of the twocontrolled switches 25, 30 is bridged in its breaker gap by a resistor.Here, too, this resistor should be of such high-ohmic type that asignificant current is only allowed to flow through coil 20 if bothcontrolled switches 25, 30 are closed.

If only the breaker gap of one of the two controlled switches 25, 30 isconnected in parallel by a resistor, only unidirectional communicationmay be available, as is illustrated with the aid of the followingexample. In this example, the breaker gap of first controlled switch 25is meant to be connected in parallel via first resistor 50, whereas thebreaker gap of second controlled switch 30 has no parallel connection.In this case, only a transmission of signals from second control device65 to first control device 60 may be done. If this communication is tobe independent of an activation of relay 5, first controlled switch 25must remain open. If second controlled switch 30 is then closed, firstdetection circuit 45 detects a potential at first connecting contact 75that corresponds approximately to ground 40. If second controlled switch30 is open, the potential detected by first detection circuit 45 atfirst connecting contact 75 is approximately equal to operating-voltagepotential 35.

Conversely, if second controlled switch 30 remains constantly open andif first controlled switch 25 is alternately open and closed, thepotential detected by second detection circuit 46 at second connectingcontact 76 remains always approximately equivalent to operating-voltagepotential 35, so that no information is able to be transmitted fromfirst control device 60 to second control device 65 via coil 20. In thisexample, the transmission of data via coil 20 may therefore only be donefrom second control device 65 to first control device 60. Conversely, ifthe breaker gap of second controlled switch 30 is connected in parallelby second resistor 55 and the breaker gap of the first controlled switchis not connected in parallel, only a unidirectional communication ordata flow via coil 20 from first control device 60 to second controldevice 65 may be done in a corresponding manner. This follows fromanalogous considerations of the voltage-divider ratios at firstconnecting contact 75 and second connecting contact 76 resulting in eachcase.

FIG. 3 shows a third exemplary embodiment of the device according to thepresent invention for triggering relay 5. In this context, identicalreference numerals again designate matching elements of the previousfigures. Like in the exemplary embodiment according to FIG. 1, firstdetection circuit 45 is arranged outside of first control 100 and seconddetection circuit 46 is arranged outside of second control 105.Otherwise, according to FIG. 3, a series circuit of first resistor 50and a third controlled switch 80 is connected in parallel to the breakergap of first controlled switch 25, third controlled switch 80 also beingtriggered by first control 100. The breaker gap of second controlledswitch 30 is correspondingly connected in parallel by a series circuitof second resistor 55 and a fourth controlled switch 85, fourthcontrolled switch 85 being triggered by second control 105.

In all other respects, the circuit according to FIG. 3 is configured asshown and described in FIG. 1. Analogously to the second exemplaryembodiment, first resistor 50 and second resistor 55 as well as thirdcontrolled switch 80 and fourth controlled switch 85, respectively, mustbe selected such in their ohmic magnitude that no significant currentflow is allowed through coil 20 when first controlled switch 25 is openand second controlled switch 30 is open. Third controlled switch 80 andfourth controlled switch 85 may likewise be embodied as field-effecttransistors, as shown in the example according to FIG. 3, or they mayhave any other design known to one skilled in the art, for example, theymay also be designed as bipolar transistors. If both third controlledswitch 80 and fourth controlled switch 85 are blocked, a situation asillustrated by circuit diagram of the first exemplary embodimentaccording to FIG. 1 results, which functions in the manner describedthere.

If either third controlled switch 80 or fourth controlled switch 85 isclosed, a defined potential will already result at first connectingcontact 75 and second connecting contact 76, regardless of the switchingstate of first controlled switch 25 and second controlled switch 30,thereby realizing an operating mode described according to FIG. 2 inwhich either the breaker gap of first controlled switch 25 or thebreaker gap of second controlled switch 30 is connected in parallel by aresistor. If both third controlled switch 80 and fourth controlledswitch 85 are closed, a situation as illustrated in the specificembodiment in FIG. 2 results, which functions in the manner describedthere.

However, in addition there is now a communication possibility betweenfirst control device 60 and second control device 65 that is completelyindependent of the triggering of relay 5 by first controlled switch 35and second controlled switch 30. For example, in de-energized relayoperation, when first controlled switch 25 and second controlled switch30 are both open, for instance, a communication between both controldevices 60, 65 may be implemented in the following manner. If firstcontrol device 60 wants to send a signal to second control device 65,fourth controlled switch 85 may be closed, for instance. If thirdcontrolled switch is then opened, second detection circuit 46 detects apotential corresponding to approximately ground 40 at second connectingcontact 76.

If third controlled switch 80 is closed, second detection circuit 46detects a potential corresponding to approximately half theoperating-voltage potential 35 at second connecting contact 76, providedfirst resistor 50 and second resistor 55 are of approximately the samesize. Conversely, when transmitting from second control device 65 tofirst control device 60, third controlled switch 80 may be closed and asignal transmission be implemented via coil 20 by opening and closing offourth controlled switch 85, the resulting potential at first connectingcontact 75 being determined by first detection circuit 45.Bi-directional communication between first control device 60 and secondcontrol device 65 via coil 20 may be done in this manner as well, bothcontrol devices 60, 65 being able to transmit simultaneously.

By energizing and de-energizing third controlled switch 80 duringtransmission mode of first control device 60, a binary signal, which hasthe two values, ground 40 and approximately one half operating-voltagepotential 35, is then generated again. Furthermore, during transmissionmode of second control device 65, a binary signal having the valuesoperating-voltage potential 35 and approximately one halfoperating-voltage potential 35 is generated by switching of fourthcontrolled switch 85.

Alternatively, the breaker gap of only first controlled switch 25 oronly second controlled switch 30 may be connected in parallel by aseries circuit of resistor and additional controlled switch. This isshown by way of example by a parallel connection of the breaker gap ofsecond controlled switch 30 via the series circuit of second resistor 55and fourth controlled switch 85, while the breaker gap of firstcontrolled switch 25 is not to be connected in parallel. Abi-directional communication may then be realized as follows, forexample:

During transmission from second control device 65 to first controldevice 60, first controlled switch 25 and second controlled switch 30are to be open. When fourth controlled switch 85 is opened, an undefinedpotential is available at first connecting contact 75. If fourthcontrolled switch 85 is closed, a potential of approximately ground 40is available at first connecting contact 75. If the undefined potentialdiffers from ground 40, a binary signal may be generated in this way andtransmitted via coil 20 from second control device 65 to first controldevice 60.

Conversely, when transmitting from first control device 60 to secondcontrol device 65, controlled switch 85 should be closed, whereas secondcontrolled switch 30 should be open. If first controlled switch 25 isthen closed, approximately operating-voltage potential 35 will beavailable at second connecting contact 76. On the other hand, if firstcontrolled switch 25 is open, approximately ground 40 will be availableat second connecting contact 76, so that a binary signal, which even hasdefined values, may be generated and transmitted from first controldevice 60 to second control device 65 via coil 20.

In a fourth exemplary embodiment according to FIG. 4, identicalreference numerals again refer to the same elements as in the previousexemplary embodiments. On the basis of the first exemplary embodimentaccording to FIG. 1, first detection circuit 45 is integrated in firstcontrol 100 and second detection circuit 46 is integrated in secondcontrol 105. Otherwise the circuit according to the fourth exemplaryembodiment according to FIG. 4 has the same configuration as the circuitaccording to the first exemplary embodiment according to FIG. 1. Inaddition, first control 60 includes a fifth controlled switch 90, whichis triggered by first control 100 and embodied as field-effecttransistor, for example. However, fifth controlled switch 90 may alsohave any other design known to one skilled in the art and be designed asbipolar transistor, for instance.

In addition, a second relay connection having a second coil 21 isprovided, which includes a third coil connection 11 and a fourthconnection, which is connected both to first relay 5 and its second coilconnection 15. Third coil connection 11 is connected to a thirdconnecting contact 77, which is in the form of a single connectingcontact of a third control connection 72 of first control device 60.Third connecting contact 77 is able to be connected to operating-voltagepotential 35 via fifth controlled switch 90. In all other respect, thecircuit according to FIG. 4 is configured as shown in FIG. 1. In thismanner, both coils 20, 21, independently of one another, are able to beconnected to operating-voltage potential 35 via first controlled switch25 and fifth controlled switch 90, respectively, of first control device60.

On the other hand, their connection to ground 40 is implemented viasecond controlled switch 30 of second control device 65. Both relays 5,6 are thus able to be activated independently of one another via firstcontrol 100 of first control device 60. If the two relays 5, 6, as shownin FIG. 4, then switch the same load-current circuit, denoted byreference numeral 110 in FIG. 4, load-current circuit 110 likewise beingconnected in a manner not shown to operating-voltage potential 35 on oneside and to ground 40 at the other side, three different and mutuallyseparate conditions may be realized for the closing of load-currentcircuit 110 by a first controlled switch 25, a second controlled switch30 and a fifth controlled switch 90.

Of course, as an alternative, the ground-side connection point of secondcoil 21 may also be connectable to ground 40, independently of secondcoil connection 15 of first coil 20, via an additional controlled switchof second control device 65, so that even four conditions for theclosing of load-current circuit 110 are able to be realized in thismanner by the two relays 5, 6.

Furthermore, as an alternative, the two connecting points, on theoperating-voltage side, of coils 20, 21 may naturally also be connectedto operating-voltage potential 35 via a common controlled switch offirst control device 60.

In addition and in a corresponding manner, more than two relays may alsobe triggered by first control device 60 and second control device 65.The different relays triggered by first control device 60 and secondcontrol device 65 may activate switches in the same load-current circuitas shown in FIG. 4 or in different load-current circuits. According toFIG. 4, first relay 5 activates a first switch 115 and second relay 6 asecond switch 120.

This series connection of first switch 115 and second switch 120 ofload-current circuit 110 is advantageous when a relay-contact pair isfused and a separation is thus ensured by the second contact pair. Ifpotential 1000 is advantageously detected at one of the contacts ofsecond switch 120 by one of control devices 60, 65, such as by firstcontrol device 60 in FIG. 4, a diagnosis of load-current circuit 110 maybe performed by individual switching of relays 5, 6.

Due to the possibility of detecting the switching state of thecontrolled switch of the one control device in the detection circuit ofthe other control device, which was already described in the firstexemplary embodiment, it may be ascertained in the other control devicewhether or not a closing of the own controlled switch activates therelay.

In the relay-operating mode of device 1, as described, in one controldevice, the switching state of the controlled switch of the othercontrol device may be detected or determined. If the communication isimplemented by changing the switching state of first controlled switch25 or second controlled switch 30, the detection of this switching stateis carried out or performed in the same way manner as in thecommunication-operating mode according to the described exemplaryembodiments. In the relay-operating mode, the switching state of thecontrolled switch of the other control device is ascertained per se, soas to check whether the relay may be activated by closing the owncontrolled switch.

In communication mode, on the other hand, it is not the switching stateper se that is important, but the bit sequence defined by thealternating switching states. For instance, in the exemplary embodimentsaccording to FIG. 2 and FIG. 3, a relay-operating mode of device 1 maybe realized in which at least one of the high-ohmic resistors 50, 55 isconnected in parallel to the one controlled switch triggering coil 20,so that the switching state of the other controlled switch triggeringcoil 20 is detectable at the coil terminal assigned to this coil 20.

Load 20 is embodied as coil in the described examples and thusrepresents an inductive load. Of course, load 20 may also have a purelyohmic design. In general, load 20 may be ohmic and/or inductive.

1. A device to control at least one electrical load, the load being acoil of an electromagnetic actuator, having a first load connection anda second load connection, comprising: a first controlled switch, whereinthe first load connection, via the first controlled switch, isconnectable to an operating-voltage potential; and a second controlledswitch, wherein the second load connection is connectable to areference-voltage potential via the second controlled switch; wherein adetection circuit is connected to at least one of the load connections,the detection circuit detecting at least one potential at a terminal ofthe at least one of the load connections; and wherein the deviceincludes an operating mode in which signaling in the form of at leastone switching state of one of the controlled switches occurs to the loadterminal of the other controlled switch via the load, and a detection ofthe voltage resulting therefrom by the detection circuit occurs at theload terminal of the other controlled switch.
 2. The device of claim 1,wherein a high-ohmic resistor is connected in parallel to at least oneof the two controlled switches.
 3. The device of claim 2, wherein ahigh-ohmic resistor is connected in parallel to each of the controlledswitches.
 4. The device of claim 1, wherein a high-ohmic resistor isconnectable in parallel to at least one of the two controlled switches.5. The device of claim 4, wherein the parallel connection of theindividual high-ohmic resistor is implemented by an associatedadditional controlled switch.
 6. The device of claim 2, wherein in anactuator operating mode, which is a load operating mode, of the device,at least one of the high-ohmic resistors is connected in parallel to oneof the controlled switches, so that the switching state of the othercontrolled switch is detectable at the coil terminal assigned to thisload.
 7. The device of claim 1, wherein, in a communication operatingmode of the device, a communication between the two load connectionstakes place via the load, by energizing or de-energizing the high-ohmicresistor at the one load connection and detecting the voltage resultingtherefrom at the respective other load connection.
 8. A control devicecomprising: at least one controlled switch; at least one controlconnection to control at least one electrical load, the load being acoil of an electromagnetic actuator, by the at least one controlledswitch; wherein the control connection to control the load includes asingle connecting contact to connect to precisely one of the connectionsof the load, and this connecting contact is connectable via the at leastone controlled switch to precisely one of an operating-voltage potentialor a reference-voltage potential; and wherein a communication occurs ina first operating mode by transmitting a signal to an additional controldevice via the load by switching the at least one controlled switch. 9.The control device of claim 8, further comprising: a detection circuitconnected to the connecting contact to detect the potential at thisconnecting contact.
 10. The control device of claim 8, wherein, in asecond operating mode of the control device, a detection of voltagelevels of signals from an additional control device transmitted via theload occurs at the connecting contact.
 11. The control device of claim10, wherein, in a third operating mode of the control device, adetection of the switching state of a controlled switch, connected toanother connection of the load, of a further control device occurs atthe connecting contact.
 12. The control device of claim 8, wherein ahigh-ohmic resistor is connected in parallel to the controlled switches.13. The control device of claim 11, wherein a high-ohmic resistor isconnectable in parallel to the controlled switch.
 14. The control deviceof claim 13, wherein the parallel connection of the high-ohmic resistoris implemented by an associated additional, controlled switch.
 15. Thecontrol device of claim 13, wherein, in a fourth operating mode, acommunication by transmission of a signal to an additional controldevice occurs via the load by energizing or de-energizing the high-ohmicresistor.
 16. The device of claim 1, wherein the first and secondconnections are provided using different control devices.